Regulator



EXAMINER AU 252 Ex lss REFERENCE FIP8Z1Z May 13, 1930.

G. F. MACHLET REGULATOR 2 Sheets-Sheet 1 Filed June 18 1926 FurtherAmplification EXAMINER E C uh E D E F E D S S 0 R u.

May 13, 1930. G. F. MACHLET REGULATOR Filed June 18. 1926 2 Sheets-Sheet2 In uenfo/c' 6 Patented May 13, 1930 UNITED. sures PATENT OFFICEApplication filed June 18,

This invention relates to means for regulating the heat of furnaces,such as shown, for example, in my Patents No. 1,068,065, of July 22,1913; No. 1,099,658, of June 9, 1914, and No. 1,306,015, of June 10,1919, and for regulating power and other apparatus, as, for example,electric circuits, and for other purposes, especially where delicateaction is involved.

In heat regulators, there has usually been employed a galvanometer,which is affected by variations in the heat of a furnace. In other casesregulation has been eflected by variations in the strength of theelectric current which is to be controlled, or by variations in theoutput of power.. The galvanometer, voltmeter or other electric'measuring device usually includes a delicate needle, whereby it hasbeen sought to secure a very close regulation, as, for example, it hasbeen the practice to maintain a furnace at say 2000 degrees, without-avariation of more than five or ten degrees of heat.

In certain of said patents, and in my Patent N 0. 1,227,921, of May 29,1917, mechanicallyoperating devices have been made to co-operate withthe galvanometer or voltmeter needle, in such a manner that the needlewould act as a mechanical interponent in the 39 mechanism. A feature ofthe present invention is that the movement .of the needle is absolutelyunobstructed, and the necessity for intricate mechanism is avoided,while the regulation is rendered very fine, even under extreme heat orother extreme conditions. The

device is inexpensive, and is readily connected to the voltmeter,galvanometer or other needle device, as well as to the furnace or otherapparatus to be regulated.

To secure these and other ends, a selenium tube or bulb, or aphoto-electric cell, or lightsensitive cell, is'exposed to light fromany suitable source, this light-sensitive cell being included in anelectric circuit, in which the power of the electric current isdependent upon theefl'ect of the li ht upon the sensitive cell, as isunderstood. be light of the lamp, which may be an electric-bulb isconcentrated 'prefe ably by the means of a convex oblong lens, anddirected through a slitnnto the sen- 1928. Serial Io. 118,801.

sitive cell. The needle of the galvanometer advances to and over thisslit as the heat of the furnace rises, or as a fluctuation occurs in anelectric powersystem or other apparatus.

Thus the light is diminished or shut off from the sensitive cell, andhence there is weakening of the current in the circuit which includessaid cell.

This fluctuation in the circuit of the lightsensitive cell is utilizedto vary the supply of fuel to the furnace, or to vary the strength ofthe electric current in a system which is to be controlled, or to effectsuch other regulation or change as may be required.

Preferably the regulation is effected in proportion to the fluctuationof heat and during such fluctuation. The regulator preferably does notturn the fuel supply wholly on or wholly off, but rather affects therate of fuel supply in proportion to the intensity of the light fallingupon the sensitive cell. The invention has in its preferred form theadvantage of reducing or increasin the rate of supply of fuel inproportion to Fhe requirements of the furnace, the flow of fuel beinguninterrupted, but being diminished or augmented. The temperature of thefurnace advances slowly, the shutter slowly diminishes the light effectupon the sensitive cell,'the galvanometer comes to rest at a goint wherethe light is only partially obscure by the shutter, and the supply offuel is slowly and evenly reduced. There may thus be brought about abalance, the supply of fuel being automatically held at a point wherethe furnace heat will neither decrease nor increase.

Preferably a special resistance amplifier, such as is commonlv used, forexample, with photo-electrical cells, is introduced in the in a way topermit rotative adjustment of the cell and frame about the axis ofmovement of the galvanometer needle, so that the regulation of thefurnace may be set to take place at any desired point. The electric lampmay be mounted upon the same frame, so as to be adjusted to ether withthe cell. The shutter portion 0 the needle may radiate from thegalvanometer pivot, and may extend oppositely'from the needle itself;and it may be of a width to cut off the light from the sensitive celllong enough for increasing the heat of the furnace to be checked, and incase it is rapidly increasing at an time.

Other features and a vantages will hereinafter appear.

In t e accompanying diagrams.

Figure 1 is a alvanometer with an adjustable selenium or ight-sensitivecell frame, this view showing also a furnace which is included in thecircuit of the galvanometer needle and which has a fuel supply which isincluded in the circuit of the lig t-sensitive cell, there being alsoincluded in the selenium circuit an am lifier.

igure 2 is an elevation, artly in section, of the galvanometer and t elight-sensitive cell and its housin adjustable thereon, showing also theelectric light bulb.

Figure 3 shows a voltmeter forming part of an electric currentregulator.

Into the flame-chamber of a furnace 10, whose heat is to be regulated,extends a fire end 11, connected by wires 12, 13, to a rotative coil orelement 14 of a galvanometer 15 as usual, the element 14 being pivotedas indicated at 16, and having a needle 17 extending over the usualscale 18, whereby may be ascertained the heat of the furnace 10.

According to the present invention, the element 14, by its rotation, isalso utilized to control the heat of the furnace. For this purpose ashutter-arm 19 radiates from said pivot 16, preferably in the oppositedirection rom the needle 17, and preferably formed in one piece withsaid needle. The use of this shutter-arm is to intercept all or part ofthe light, which is caused to fall from an electric lamp 20 upon aselenium, photo-electric, or other li ht-sensitive cell, tube, or bulb21. This lig t-sensitive cell 21 is within a dark housing 22, havingalong its top a narrow slit 23, permitting light to enter from the lamp20. An oblong lens or light-focusing device 24 above said slit serves toconcentrate the light from the lamp 20 and increase the efficiency ofthe apparatus. The shutter 19-may swing freely in the space between thelens and the slit 23, the boxwork of the wall of the galvanometer 15having a horizontal slot 25 to permit this motion, and an open or clearspace being left at 26 above the housing 22, for the same purpose. Whilethe furnace is heating up and the needle 17 and the shutter 19 areswinging, the light from the lamp a) shines same circuit is a battery orsource of ower 29 and an amplifier, which is general y designated as A;the amplifier being of a construction usual in radio-receivin sets andin other arts, being usually in the form of the wellknown tube. From thebattery 29 a conductor 30 of said circuit extends to a solenoid 31, andfrom the latter there extends a return conductor 32 to the amplifier A,the effectof the amplifier being to augment the power of the solenoid31. By the rising and falling of the core 33 of said solenoid, thesupply of fuel to the furnace 10 is regulated.

The fuel usually consists of gas from a main 34 and compressed air froma main 35, which enter a mixer, designated as M, from which the mixedfuel is delivered through a pipe 36 to a manifold 37, from which extendburners 38 into the frame-chamber of the furnace 10. In the mixer arevarious ports which are opened and closed by means of poppet-valves 39mounted upon a common stem 40, the lower end of which is joined to abellows-like drum 41, which is in the form of a thin-walled coppercylindrical box having peripheral corrugations or pleats which permitthe drum to lengthen and shorten according to the variation in airpressure therein, the air entering from a tube 42. Increase of pressurecauses the drum or diaphragm 41 to expand and thereby lift the stem 40and the oppet-valves, while a decrease in pressure as the oppositeeffect, closing the ports.

From the compressed air main 35 extends a nozzle 43 into which .0 ensthe end of the diaphragm tube 42; an a needle or other valve 44 may .beprovided in said nozzle between the tube 42 and the main 35, to controlmanually the pressure of air in the tube 42 and in the diaphragm 41. Thenozzle is also provided with an outlet 45, forming a continuing leak,which is reducible by a stem or closure 46 extending up from thesolenoid core 33,

From the foregoing it will, be understood that when the shutter 19 ofthe galvanometer partially closes the slit 23 and thereby partly shutsoff the light-sensitive cell 21 from receiving light, the electriccurrent in the circuit of said cell is weakened accordingly, and hencethe power of the solenoid 31 is reduced, an the core 33 drops more orless.

thereby opening more or less the leak 45 and permitting waste ofcompressed air from the nozzle 43, whereby, the pressure in the tube 42is reduced, as well as in the drum or' diaphragm 41, which contracts, sothat its stem 40 descends, together with all of the pop etvalves 39, andthe supptliy of fuel to the urnace is reduced or cut 0 Upon the heat ofthe furnace falling, the galvanometer is affected accordingly, and theshutter 19 rotates, thereby uncovering more of the slit 23, andaffecting the light-sensitive cell circuit accordingly, and increasingthe power of the solenoid 31, whereby the core 33 is lifted and theleakage at is reduced, and the pressure in the tube 42 and diaphragm 41is raised accordingly, and the valves 39 hence are opened and the supplyof fuel to the furnace is increased.

It will be noted that there is entire absence of any obstruction oropposition to the movement of the needle 17 or shutter 19, so that thesame may be extremely sensitive in operation and yet positively controlthe heating of the furnace in a simple manner. The control is quicklyefiected, and a furnace may be maintained at heat of thousands ofdegrees with negligible fluctuation. The shutter by only partiallyclosing the slit 23 may effect sufficient weakening of the current inthe selenium cell circuit as to barely open the leak 45, and permit analmost imperceptible constant or continuous waste of air from the nozzle43, but still sufiieient to keep theair pressure in 42 and 41 at theexact pointfor supplying just enough fuel to maintain the heat of thefurnace at that point substantially v without any variation; the entireapparatus being very sensitive, while at the same time eflicient tocontrol the furnace.

For using the device at difi erent de rees of heat, an adjustment isprovided. A racket or frame 47 is pivoted upon a shoulder 48 of a 'stud49, rising from the top of the casing of the ga-lvanometer 15, saidbracket carrying at one end a bent arm 50 supporting the electric-lightbulb 20, and carrying at its other end the housing 22 of the seleniumcell, whereby the bracket, the housing and the light may be adjusted asa unit concentrically with the rotary element 14 of the alvanometer, athumb-nut 51 being threade upon the stud 49 to secure the parts whereadjusted. The adjustment may be aided by means of an index 52 carriedupon the bracket and co-operative with the usual scale 18 of thegalvanometer.

The amplifier unit is of well-known construction, and, may include an l8-volt bat tery 53, a grid leak 54, a 6-volt battery 55 and the usualtube 56. The invention is not limited to the use of an amplifier in thesame circuit with the light-sensitive cell and the solenoid, for theinvention includes broadly 'cRoss REFERENCE nometer may be utilized inreglililating other apparatuses or elements than rnaces.

At Figure 3 a voltmeter 57 is connected to the power mains 58, 59,leading from a dynamo 60. The voltmeter is provided with the shutter-arm19, to cover a light slit 23 over a light-sensitive cell 21, as in theother views, the circuit of the sensitive cell including wires 27, 28,-amplifier A, battery 29 and wires 30, 32, the latter leading to and froma magnet 61. By means of thls magnet and its pivoted armature 62, thereis kept closed or nearly closed a jet63, similar to 43, from whichcompressed air leaks; this jet or nozzle leading from a ipe 64, in whichair is kept under pressure y a pump or blower 65. Also connected to pipe64 is a large expansible drum 66, corresponding with 41, which ismaintained in expanded condition by the compressed air therein. To thetop of the drum is pivoted a switch-arm 67, operating upon rheostat 68included in said main circuit 58, 59. When the current in the dynamocircuit is below normal, the light slit 23 remains open, and a strongcurrent is maintained in the sensitive-cell circuit, and the maglnet 61keeps the leak 63 practically closed, so t at there is high air pressurein the drum or diaphragm 66, and. the switch-arm 67 is kept at its upperposition, cutting out much of the resistance 68. When the current in thedynamo circuit increases to the desired point, the slit 23 is wholly orpartially covered by the shutter 19, and through the described train theair pressure in the drum 66 is weakened, and it collapses to a certainextent, lowering the switch-arm 67 and thereby cutting more resistanceinto the dynamo circuit.

Variations may be resorted to within the scope of the invention, andportions of the im rovements ma be used without others.

aving thus escribed my invention, I claim:

1. The combination with an element or apparatus subject to fluctuations,of means includin a galvanometer or the like includin a iutter movableby fluctuations in the ga vanometer' circuit, a light-sensitive cell, ahousin therefor having a 1i ht-receiving slit closa le by said shutter,an means controlled hy said light-sensitive cell for regulating saidelement or apparatus, said regulating means including a coil in circuitwith EXAMINER said lightsensitive cell, an amplifier in the same circuitwith said coil and cell, and a regulating device having an independentsource of power and including a controller for said power operated bysaid coil.

2. The combination with an element or apparatus subject to fluctuations,of means including a galvanometer or the like including a shuttermovable by fluctations in the ga vanometer circuit, a light-sensitivecell, a housing therefor having a light-receiving slit closable by saidshutter, a coil in circuit with said cell, and means controlled by saidlightsensitive cell through said coil for regulating said element orapparatus, said cell-circuit including a step-up device whereby weakvariations in current caused by the effect of the galvanometer shutterupon the lightsensitive cell effect strong variations in current in saidcoil, an independent source of power under control of said coil, andmeans to enable said source of power to regulate said apparatus.

3. In combination, a galvanometer having a movable shutter-arm, aphoto-electric cell, a housing therefor having a slit, a lamp mounted toshine through said slit upon said cell, said slit closable by saidshutter-arm, the advancing shutter covering or obscuring the slit inproportion to its advance, and diminishing the conductivity of thephoto-electric cell in proportion as the light is obscured by saidshutter-arm, an amplifying device in circuit with said cell, and anindependent source of power through which said cell-circuit is connectedto operate a regulator for heat,-

power or electricity, said independent source of power being controlledby a device in said cell-circuit.

4. In combination, a galvanometer having a movable shutter-arm, aphotoelectric cell, a housing therefor having a slit, a lamp mounted toshine throu h said slit upon said cell, said slit closablc y saidshutter-arm, the advancing shutter covering or obscuring the slit inproportion to its advance, and diminishing the conductivity of thephoto-electric cell in proportion as the light is obscured by saidshutter-arm, an amplifying device in circuit with said cell, saidamplifier being included in the same circuit with said photoelectriccell, and an electrically-operated regulator controlled by said circuitand having means to regulate heat, power or electricity.

5. In combination, a galvanometer having a movable shutter-arm, aphoto-electric cell, a housing therefor having a slit, and a lampmounted to shine throu h said slit'up'on said cell, said slit closable ysaid shutter-arm,

said housing and cell carried upon a frame which is adjustably mountedto permit said shutter-arm to effect regulation at different selectedpoints in the movement of the galvanometer shutter-arm.

6. In combination, a galvanometer having a movable shutter-arm, aphoto-electric cell, a housing therefor having a slit, a lamp mounted toshine throu h said slit upon said cell said slit closable by saidshutter-arm, said housing and cell carried upon a frame which isadjustably mounted to permit said shutter-arm to effect regulation atdifferent selected points in the movement of the galvanometershutter-arm, said galvanometer having a scale, and an index toco-operate there with in setting the adjustable device.

7. In combination, a galvanometer having a movable shutter-arm, aphoto-electric cell, a housing therefor having a slit, a lamg mounted toshine through said slit upon sai cell, said slit closable by saidshutter-arm, said housin and cell carried upon a frame which is adustably mounted to permit said shutter-arm to effect regulation atdifferent selected points in the movement of the galvanometershutter-arm, said galvanometer having a scale, an index to co-operatetherewith in setting the adjustable device, and a lamp mounted upon saidadjustable frame to shine through said slit upon said cell.

8. The combination of a galvanometer circuit including a part affectedby the condition of a generator to be regulated, and which sets up acurrent in said circuit, said galvanometer having a movable shutteraffected by the strength of the current, a light-sensitive cell, ahousing therefor having an opening for the reception of light, saidshutter mounted to be capable of closing said opening, a lamp to shinethrough said opening upon said cell, said light-sensitive cell beingincluded in a circuit having a battery or other source of power and alsohaving an am lifier inclusive of an amplifier tube, a coil, included inthe same circuit with said amplifier and said cell, and agenerator-regulating device controlled by saia coil.

9. The combination of a galvanometer circuit including a part afi'ectedby the condition of a generator to be regulated, and which sets up acurrent in said circuit, said galvanometer having a movable shutteraffected by the strength of the current, a light-sensitive cell, ahousing therefor havin an opening for the reception of li ht, saidshutter mounted to be capable of'c osing said opening, a lamp to shinethrough 'said opening upon said cell, said light-sensitive cell beingincluded in a circuit having a battery or other source of power and alsohaving an amplifier inclusive of an amplifier tube, a coil included inthe same circuit with said am lifier and said cell, agenerator-regulating evice controlled by sald coil, said generator inthe form of a furnace, means for supplying fuel to said furnace, andmeans controlled by said regulating coil for varying the supply offuel-to the furnace,

10. Heatregulating nieans for a furnace,- including an expansi le drumor diaphragm :fikl'flblfi by com ressed air and controlling e supply offue to said furnace, and a galvanometer circuit having a thermoticelement affected by the fluctuations in the heat of the furnace, ashutter element operated by said alvanometer, a light-sensitive cell, ahous mg therefor having a slit which may be opened and closed by saidgalvanometer shutter, means for permitting the pressure of air in saiddrum or diaphragm to leak, and means controlled by said sensitive cellto close and open said leak.

11. The combination with an element or apparatus subject tofluctuations, of means including a galvanometer or the like including ashutter movable by fluctuations in the galvanometer circuit, alight-sensitive cell, a

housing therefor having a light-receiving slit closable by said shutter,means controlled by said light-sensitive cell for regulating saidelement or apparatus, said galvanometer having an adjustable frame orbracket pivoted thereonconcen'trically with the rotative dea vice of thegalvanometer, said sensitive cell carried upon said frame foradjustment, a light bulb upon said frame, and an index to co-operatewith said frame in adjusting the same.

12. A heat-controlling rheans for a furnace, said controlling meansincluding a galvanometer circuit having a thermotic element aflected bythe fluctuations in the heat of the furnace, a shutter-element operatedmore.or less by said galvanometer, according to fluctuations in thegalvanometer circuit. an electrical controller including both alight-sensitive cell and a housing therefor having a slit which may beopened and closed bysaid galvanometer-shutter, the fluctuations of saidelectrical controller being dependent upon variations in the current inthe light-sensitive cell-circuit effected by said shutter, and meansgoverned by said electrical controller for determining the supply offuel.

13. In a fuel-supply-regulating means for a gas furnace having a set ofair. and gas mixing valves 'and also having a galvanometer circuitincluding a thermotic element afiected by the fluctuations in the heatof the furnace, the combination of a shutter operated by saidgalvanometer, a light-sensitive cell, a housing therefor having alight-opening closable by said shutter, a source of light to shinethrough saidopening upon said cell, said light-sensitive cell beingincluded in a "second circuit having a source of power and also havingan amplifier inclusive of an amplifier tube, a c011 being also includedin said second circuit, a drum having a controlling stem joined to saidvalves, said drum formed of flexible metal and having circumferentiallyplated sides and expansible by air pressure, a connection from said drumto the supply of compressed air to said mixing valves, and meansconoRoss REFERENCE trolled b said coil to vary the pressure of air insaid rum.

14. The combination with a furnace havin a supply of gas and a supply ofcompressed air and a set of mixing and controlling valves, and alsohaving a galvanometer circuit including a thermotic element affected bythe fluctuations of heat in the furnace, of a shutter-element controlledby said galvanometer,

a light-sensitive cell, a source of light, a housing for said cellhaving a slit which may be opened and closed b said shutter, a solenoidin a circuit contro ed by said cell, a drum Y EXAMINER connected tooperate said valves and having a connection from its interior to saidsupply of compressed air, said drum formed of flexible sheet-metal andhaving sides formed of be]- lows pleats, and being longitudinallyexpansible and contractible,-and means controlled by said solenoid tovary the pressure of air in said drum and thereby control its elongationor contraction for operating the valves.

15. The combination with a furnace having a supply of gas and a supplyof comfirl'lessed air and a set of mixing and controlg valves, and alsohaving a galvanometer circuit including a thermotic element affected byfluctuations of heat in the furnace, of a light-sensitive cell, ashutter-element operated by said thermotic element and controlling thelighting of said cell, a solenoid in a circuit controlled by said cell,an expansible sensitive cell, a shutter-element operated bysaidthermotic element and controlling the lighting of said cell, a solenoidin a circuit controlled by said cell, an expansible drum connected tooperate said valves and having a connection from its interior to saidsupply of compressed air, said drum provided with a leak, and a closurefor said leak controlled by said solenoid to va the pressure of air insaid drum and there y control its expansion and contraction, foroperating the valves. 17. The combination with a furnace having a supplyof gas and a supply of comressed air and a set of mixing and controlngvalves, and also having a galvanometer circuit including a thermoticelement aifected by fluctuations of heat in the furnace, of alight-sensitive cell, a shutter-element operated by said thermoticelement and controlling the lighting of said cell, a solenoid in a ysaid solenoid to of air in said drum and thereby control its e ansionand contraction, for operating the va ves, and a manually regulatablevalve betvlveen said drum and said compressed air sup- P 18. Thecombination with a furnace having a supply of gas and a supply ofcompillessed air and a set of mixing and controlg valves, and alsohaving a galvanometer circuit including a thermotic element afl'ected byfluctuations of heat in the furnace, of a light-sensitive cell, ashutter-element operated by said thermotic element and controlling thelighting of said cell, a solenoid in a circuit controlled by said cell,a drum formed of thin flexible sheet-metal and having sides formed ofbellows pleats, and being longitudinally expansible and contractible tocontrol.said valves, a separate connection between the interior of thedrum and the comprressed air supply, and a nozzle extending om saidcompressed air supply, said nozzle having a leak, and said solenoidhaving a closure for said leak.

19. The combination of a heating apparatus to be regulated, agalvanometer controllable by said apparatus and affected by the heatthereof, and having a movable shutter, a light-sensitive cell dominatedby said shutter, an electric circuit including said cell, a pneumaticdevice having a leak, magnetic means being included in said cell circuitfor controlling said leak, and a regulator for said heating apparatuscontrolled by said pneumatic device. a,

20. In combination, with an apparatus to be regulated, a galvanometercircuit, the needle of which has a delicate shutter form and issensitively movable by reason of fluctuations in the current, alight-sensitive cell dominated bysaid shutter, said shutter having asubstantially great range of idle movement without dominating said cell,permitting the regulated apparatus to reach approximately the desiredstage of efliciency before regulation begins, and a regulating circuitincludmg said cell; whereby delicate regulation oflthe apparatus issecured in a short range of movement of the shutter around the point ofdesired efliciency of the apparatus.

21. In combination, with an apparatus to be regulated, a galvanometercircuit, the

ting the regulated apparatus toreach apneedle of which has a delicate.shutter form.

and is sensitively movable by reason of fluctuations in the current, alight-sensitive cell dominated by said shutter, said shutter having asubstantially great range of idle movement without dominating said cell,permitfor said leak conroximately the desired stage of cficiency foreregulation begins, and a regulating circuit including said cell; saidshutter and cell being mounted for relative adjustment, to predeterminethe stage at which regulation shall begin.

22. The combination with a member to be regulated, of a pneumaticregulator having a continuously operating leak, an electric circuithaving means for delicatel varying the rate of flow of air through saileak and thereby controlling said regulator, and means for automaticallyvarying the flow of current through said circuit.

23. The combination with a member to be regulated, of a pneumaticregulator having a continuously operating leak, an electric circuithaving a light-sensitive cell and also having means for delicatelyvarying the rate of flow of air through said leak, and means forautomatically controlling the supply of light to said cell.

24. The combination with a member to be regulated, of a pneumaticregulator having a continuously operating leak, an electric circuithaving a light-sensitive cell and also having means for delicatelyvaryin the rate of flow of air through said leak, an a master electriccircuit having a sensitively moving shutter dominating said cell.

25. The combination with a member to be regulated, of a pneumaticregulator having a continuously operating leak, an electric circuithaving a light-sensitive cell and also having means for delicatelyvarying the flow of air through said leak, and a master electric circuithaving a sensitively moving shutter dominating said cell; means beingprovided for afiording a preadjustment between said shutter and saidcell.

26. The combination with a re latable apparatus subject to fluctuations,o a lightsensitive cell, an enclosure therefor having an opening for theadmission of light thereto, a shutter for said opening, said shuttersensitive to the fluctuations ,of said ap aratus, an electric circuitincluding said hg tsensitive cell, a pneumatic device including adiaphragm or pneumatic member having a continuously operating air leak,magnetic means in said circuit for delicately varying the rate of flowof said air leak and thereby controlling the movement of said diaphragm,and means under the control of said diaphragm for efiecting regulationof said apparatus.

27. The combination with a re atable apparatus subject to fluctuations,o a light- ,sensitive cell, an enclosure therefor having an opening forthe admission of light thereto, a shutter for said opening, said shuttersensitive to the fluctuations of said apparatus, an electric circuitincluding said hghtsensitive cell, a pneumatic device including adiaphragm or pneumatic member having a continuously operating air leak,magnetic means in said circuit for delicately varying the rate of flowof said air leak and thereby controlling the movlnent of said diaphragm,and means under the control of said diaphragm for effecting regulationof said apparatus; means being provided for allording relativepreadjustment between said opening and said shutter, for predeterminingthe point at which regulation of said apparatus shall take place. v

28. The combination with a regulatable apparatus subject tofluctuations, of an instrument whose movements are sensitivelycontrolled by said fluctuations, a pneumatic device capable of effectingregulation of said apparatus, said pneumatic device having acontinuously operating air leak, and means under the control of saidsensitive instrument for delicately varying the rate of escape of airthrough said leakand thereby controlling the movements of said pneumaticdevice.

29. The combination with a regnlatable apparatus subject tofluctuations, of an instrumentwhose movements are sensitively controlledby said fluctuations, a pennmatic device capable of effecting regulationof said apparatus, said pneumatic device having a continuously operatingair leak, and means under the control of said sensitive instrument fordelicately varying the rate of escape of air through said leak andthereby controlling the movements of said pneumatic device, saidleak-regulating means including a light-sensitive cell whose lightsupply is controlled by said sensitive instrument, and an electriccircuit including said light-sensitive cell and a magnetic valve forsaid leak.

30. The combination with a regulatable apparatus subject tofluctuations, of an instrument whose movements are sensitivelycontrolled by said fluctuations, a pneumatic device capable of effectingregulation of said apparatus, said pneumatic device having acontinuously operating air leak, and means under the control of saidsensitive instrument for delicately varying the rate of escape of airthrough said leak and thereby controlling the movements of saidpneumatic device, said leak-regulating means including a li htsensitivecell whose light supply is controlled said sensitive instrument, and anelectric circuit including said light-sensitive cell and a magneticvalve for said leak, said sensitive instrument mounted for oscillation,and said cell being mounted for adjustment around the center of saidoscillation, to predetermine the point at which regulation shall takeplace.

31. The combination with an apparatus to be regulated, of an electriccircuit including a needle whose movements are sensitively affected byfluctuations in said apparatus, a light-sensitive cell, said needlehaving a part moving therewith to control the supply of light to saidcell, an electric circuit includin said celland also including amagnetically movable valve, and a pneumatic device having means tocontrol said apparatus and also having a continuousl operating leakthrou h which the flow of air is delicately varied by said valve.

32. The combination ofa heating apparatus, an electric circuit includinga shutter sensitively affected by fluctuations in the heat of saidapparatus, a light-sensitive cell dominated by said shutter, an electriccircuit including said cell and a magnetic valve, and an air-pressuredevice controlling the heat of said apparatus and having a continuouslyoperating leak through which the passage of air is delicately varied bysaid valve.

33. Heat regulating means for a furnace having a fuel-controlling means,said regulating means including a galvanometer circuit including athermotic element afi'ected by the fluctuations in the heat of thefurnace, a shutter element controlled by said galvanometer, alight-sensitive cell, a housing therefor having a slit which may beopened and closed by said shutter, a solenoid in a circuit controlled bysaid cell, and means to enable said solenoid to control the operation ofsaid fuel-controlling means.

34. The combination of a galvanometer having a moving element, a circuitincluding said galvanometer, a shutter movable by the current in saidcircuit, a light-sensitive cell dominated by said shutter, an adjustablemount for .said cell upon said galvanometer affording adjustment of thecell along the path of the moving element of the galvanometer, anelectric circuit including said cell and a regulating device controlledby. sai electric circuit.

GEORGE F. MACHLET.

